Thesis defence « Grassland species root functional strategies to face abiotic and biotic stresses »

Abstract
In order to optimise grassland ecosystem services we need to improve our understanding of root system functioning. As a result, we decided to characterise strategies of species coming from grassland’ Fabaceae and Poaceae families, by root functional traits measurement.
The main result of this work is the establishment of several axes of root strategies differentiation. The main axis is the trade-off between resources capture and conservation
strategies. Species with capture strategies appear to be adapted to non-water stressful habitat and are barely impacted by phosphorus shortage; they also happen to be strong competitors.
On the opposite, species with conservation strategies are adapted to water stressful continental climates, but are strongly impacted by phosphorus shortage and happen to be weak competitors. The kind of relation between above-ground and below-ground strategies also appears to be a marker of the plants adaptation to stress.
We showed that the root system study is a good way to predict grassland species comportment to face abiotic and biotic constraints. The present work widens interesting perspectives for the sowing of mixed grassland species better adapted to their environments.